Monoclonal antibodies to the B16 melanoma produced by syngeneic C57B1/6J mouse spleen cell hybridomas will be used to (1)\study tumor specific and tumor associated antigens of F1 (low metastatic potential) and F10 (high metastatic potential) variants, and (2)\test a novel immunotherapy model, using tumor associated monoclonal antibody as a protein antigen to which cell-mediated immunity will be selectively induced. Ten stable hybridomas producing monoclonal antibodies to a B16-F10 tumor associated membrane antigen have been produced already by hybridization of S194/5.XXO.Bul myeloma cells and spleen cells of B16-F10 bearing mice. The antigen is a soluble antigen contained in the membranes of F1 and F10 bearing mice. The F1 variant contains larger quantities of the antigen, partly because F10 cells show antigen shedding when treated with antibody. The monoclonal antibodies cause stable tumor cell clumping in vitro that could influence metastatic potential in vivo. The effect of cytotoxic and non-cytotoxic antibodies on B16 growth and metastasis in vivo will be investigated. New monoclonal antibodies will be produced to determine if C57B1/6J mice recognize different classes of B16 tumor antigens, similar to human melanoma cells, and if there are antigenic determinants specific to F1 and F10 variants, associated with metastatic potential. B16 cells will be analyzed for soluble and membrane-bound antigens using a variety of immunochemical techniques. Monoclonal antibody will be used to test a passive immunotherapy model. Delayed hypersensitivity to idiotypic determinants of antibody will be induced selectively in C57B1/6J mice by sensitization to dodecanoyl lipid-conjugated antibody. Sensitized mice bearing the B16 melanoma will be treated with monoclonal antibody. A cell-mediated immune reaction with antibody at the surface of the tumor cells could be cytotoxic and show an immunotherapeutic result.